The present invention relates to an apparatus and a method for diagnosis of power appliances, and, particularly, relates to a diagnosis apparatus and a diagnosis method which are suitable for diagnosing insulation, abnormal current conduction, and foreign matter mixing in gas-insulated power appliances.
In recent years, a demand for reliability of supply and for improvement in quality in environment of utilization of electric power has become greater with the advance of a highly information-oriented society and with the increase of dependency on electric power in the human living environment. With this demand, maintenance techniques for preventing accidents in operating equipment in an electric power station and for taking measurement in the event of accidents have been desired. For example, in a power appliance of a gas-insulated switchgear constituting one equipment in an electric power station, it is necessary to monitor functions thereof, such as an insulating function, a current-conduction function and the like. A method for detecting abnormality in the functions, that is, abnormality such as partial electric discharge, foreign matter mixing and the like, is described in Hitachi Review, Vol. 70, No. 3, August, 1988, pages 105 to 112.
In such a conventional technique, means for detection of partial discharge, detection of abnormal current conduction, and detection of foreign matter mixing in a power appliance is constituted by separately provided individual detection systems. In the case where there are many places to be detected, therefore, the number of detectors is increased so that the number of local panels for housing those detectors is increased. There arises therefore a problem in that not only cost becomes high but reliability is lowered because of use of a large number of detectors.